It really isn't that difficult. What I used was the UDE + xboxhdm package. Use the search to find it and just download both xboxhdm and UDE and put the UDE folder in the root directory (/linux). Use the make-iso-win.bat utility to make an iso then burn it onto a cd. Look on
www.xbox-scene.com for a tutorial on hotswapping.
Hotswap the xbox hd into the PC (make sure you've enabled booting from CD first - a reset means you will have to do the hotswap again) Just press enter when linuxhdm boots and when you get to the prompt type UDE -UDE2. Everything should install and from there just close everything and put the xbox hd back into the xbox.
Don't worry if you get service error 12 (I did), just reset it a few times until evox comes up. If it doesn't, try putting a cd in and then loading from HD again. If this doesn't work, then I suggest you mess around with linuxhdm and formatting the HD and trying again..look on the forums for linuxhdm for help. In the end everything -should- work. If it doesn't, you can try slayers and using it to reload your HD back to normal (I haven't tried this yet, but supposedly it works. It's my next step because while experimenting I did format first and couldn't back up the original dashboard.)
Once evox comes up, you can just follow what sveetsnelda said. If your evox doesn't have Flash BIOS in the system utils menu, download the version off of the usual place and use that evox.ini. The next thing you need to do is add the Flash = 0x01AD,"X-ecuter 3",0x100000 line with the other ones into evox.ini and then finally transfer it over. (Everything is based in the "fonts" folder in the C partition, so don't bother putting it in just C - put it in fonts) Stick the bios files in C:\fonts\bios and they should come up. The next step I had little trouble with, though my xbox DID go crazy twice, shutting off and on until I plugged the power out. If this happens, don't worry, just leave the power off for a tiny bit and plug it back in and everything should work correctly.
Now you need to start up the xbox without the chip in and wait for Evox to load. Now, CAREFULLY plug the chip in. Make sure that your switch is set to "on on off off" Go to system utils - > Flash BIOS and select the 16plus bios. If the codes that come up are 01AD, you did everything right. Press Y to flash, start up the xbox with the chip on, and the x3 bios should come up. Have fun with your now working X3
